Members of the lentivirus family, which includes Human Immunodeficiency Virus type 1 (HIV-1), are pathogenic retroviruses that induce chronic, degenerative diseases in their animal hosts. The genomic organization and regulatory mechanisms of the lentivirus family have been found to be more complex than those of other member of the retrovirus family. For example, the genome of HIV-1 encodes the virion proteins Gag, Pol and Env which are common to all replication competent retroviruses, two additional proteins which are necessary for virion morphogenesis and maturation (Vif and Vpu), a protein of unknown function (Vpr), and three nonstructural regulatory proteins (Tat, Rev, and Nef).
The Tat and Rev gene products are trans-activating proteins which regulate HIV-1 gene expression by specific interaction with structured viral RNA target sequences. Because of their importance as potential targets for chemotherapeutic intervention in HIV-induced disease, these trans-activators have been the subject of intense scientific scrutiny.
In addition to the lentiviruses, almost all DNA viruses encode transcriptional trans-activators of viral gene expression. For example, human T cell leukemia virus type 1 (HTLV-1) encodes a transcriptional activator termed Tax, which like the HIV-1 Tat protein acts to greatly amplify viral gene expression. HTLV-1 also encodes a trans-activator, termed Rex, which is required for the expression of the incompletely spliced mRNAs that encode the HTLV-1 Gag, Pol and Env gene products. Recent studies have shown that HTLV-1 Rex protein can functionally replace the HIV-1 Rev polypeptide and rescue replication of a Rev deficient HIV-1 provirus.
Although such intracellular proteins have been recognized as potential targets for intervention, efforts toward this end have been unsuccessful. An effective method for targeting and inactivating such intracellular proteins would be broadly applicable.
The subject invention relates to a method for targeting an intracellular protein for interaction with an antibody in a cell by contacting the cell with a cationized antibody which binds specifically to the intracellular protein. The specific binding of the cationized antibody to the intracellular protein can be used to accomplish a variety of goals. For example, the binding of the antibody to the intracellular protein can be used to interfere with the activity of the intracellular protein. This is particularly important when the activity of the intracellular protein has a deleterious effect on the host cell. This is the case, for example, with the HIV-1 encoded Tat protein.
Alternatively, the specific binding of the cationized antibody to the intracellular protein can be used in a method for detecting the presence of a particular intracellular protein in a cell. For such an application, the cationized antibody would be labeled with a detectable reporter group.
The methods of the invention are applicable both in vivo for immunotherapeutic or diagnostic uses, and in vitro for research and diagnostic use. A preferred in vivo immunotherapeutic method can be used for treating an individual infected by a virus, for example, HIV-1. An effective amount of a cationized antibody in a pharmaceutically acceptable formulation is administered to the individual.
The methods and compositions disclosed in the subject application offer a new and effective approach for the targeting of an intracellular protein which is based on the discovery that cationized proteins are not necessarily sequestered in intracellular vesicles when taken up by a cell, contrary to the teaching of the prior art.